ESP32Synth : An Audio Synthesis Library For The ESP32

April 23, 2026 by 1 Comment

With MCUs becoming increasingly more powerful it was only a matter of time before they would enable some more serious audio-processing tasks. [Danilo Gabriel]’s ESP32Synth library is a good example here, which provides an ESP-IDF based 80+ voice mixing and synthesis engine. If you ever wanted to create a pretty impressive audio synthesizer, then all you really need to get started is an ESP32, ESP32-S3 or similar dual-core Espressif MCU that has the requisite processing power.

Audio output goes via I2S, requiring only a cheap I2S DAC like the UDA1334A or PCM5102 to be connected, unless you really want to use the internal DAC. With this wired up you get 80 voices by default, with up to 350 voices demonstrated before the hardware cannot keep up any more. You can stream multiple WAV files from an SD card for samples along with the typical oscillators like sinewave, triangle, sawtooth and pulse, as well as noise, wavetables and more.

In order to make this work in real-time a number of optimizations had to be performed, such as the removal of slow floating-point and division operations in the audio path. The audio rendering task is naturally pinned to a single core, leaving a single core for application code to use for remaining tasks. While the code is provided as an Arduino project, it uses ESP-IDF so it can likely be used for a regular ESP-IDF project as well without too much fuss.

2026 Green Powered Challenge: Cook With The Sun!

April 23, 2026 by 3 Comments

One of the problems facing any solar power installation comes in storing enough power for high-intensity operations such as cooking. The high-tech and expensive way involves battery banks and inverters, but [Solar Genius] is taking a more direct route by skipping the energy storage entirely.

A pair of parabolic antennas are pressed into service as mirrors, catching and focusing the sun’s energy onto a cooking pot. Of course, solar cookers like this are nothing new, so what makes this one different is the in-depth analysis of its performance. This thing can cook!

One antenna is covered in square mirrors while the other is covered in sticky chrome-effect mirror sheeting. They’re described as sun tracking, but since we don’t see any mechanism we’re guessing the tracking is done by hand. The experiment takes place in Pakistan, so there’s a plentiful supply of sunlight that those of us in more northern climes can only dream of.

This hack is part of our 2026 Green Powered Challenge. You’ve just got time to get your own entry in, so get a move on!

2026 Hackaday Greep Powered Challenge

A Solar Powered Plant Monitor That Almost Works

April 23, 2026 by 3 Comments

Keeping plants alive is easy if you’re diligent and never forget to check on your green friends. However, a little electronic help never hurts. To that end, [Narrow Studios] built a simple solar powered monitor to assist in plant maintenance, and it mostly does the job.

An ESP32-C3 development board serves as the brains of the operation. It’s set up with a capacitive soil moisture sensor, a great choice because they tend to last longer than other types. Power is courtesy of a small lithium-polymer battery and a solar panel, which keeps everything running off the juice from interior lighting alone. SK6812 addressable LEDs are used to show current soil moisture status. To avoid excessively draining the batteries with the limited power available, a HCSR505 PIR motion sensor is used to only light the status LEDs if the device detects someone in the vicinity.

There were some issues in the build. The voltage regulator doesn’t supply enough current to enable the ESP32 to jump on WiFi, so soil dryness indication is via LED only. The solar setup is a little weak, too. Still, the project was a great learning experience and with a few mods, would be even more capable.

We’ve featured some great plant monitors over the years, like this Hackaday Prize entry from 2023.

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VCF East And Maker Faire Make For A Busy Weekend

April 23, 2026 by 6 Comments

For those of us with an interest in hacking and making, events where we can meet up with like minded folks and check out the projects they’re working on don’t exactly happen every day. Unless you’re able to travel around the country (or even better, the world), you usually have to make do with the handful of annual events that are within a reasonable distance of your home. If you’re lucky that may give you two or three opportunities during the year to look forward to, generally spaced out enough that you’ve got adequate time to prepare ahead of the event and decompress afterwards.

But occasionally, the planets and geekdoms align. Such was the case this past weekend in the Northeastern United States, with Vintage Computer Festival East and the Philadelphia Maker Faire taking place simultaneously. Both are established must-see events for their respective communities and cover roughly the same geographical area, so if you happened to have a foot in each camp, this presented quite a difficult decision.

That is unless you took the third option. As the Philly Maker Faire was on Sunday and VCF took place over the span of the whole weekend, there was a narrow path to attend both events. It wouldn’t be ideal, of course. For one thing it would mean speed running VCF East, and there was a couple hundred miles of travel to contend with. We won’t even talk about the physical toll incurred — while there doesn’t appear to be any official dosage recommendation from the Surgeon General, surely this level of exposure to non-conforming technologists carries with it some risks.

But sometimes such sacrifices must be made, especially if you’re being paid to make them. So I packed up twice the normal number of Wrencher stickers, and hit the road in an effort to deliver a condensed version of my experience at these two fantastic events.

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KernelUNO, An OS For The Arduino Uno

April 23, 2026 by 25 Comments

If you were to point to a single device responsible for much of Hackaday’s early success, it might be the Arduino Uno. The little board from an Italian university with its easy to use dev environment changed microcontroller hacking forever, and while it’s now very much old hat, its shadow lies long across single board computing.

Just in case you thought there wasn’t much more life in that old AVR in 2026, along comes [Arc1011], with KernelUNO, describing itself a “A lightweight RAM-based shell for Arduino UNO with filesystem simulation, hardware control, and interactive shell“. It’s an OS for your Arduino, of sorts.

For flashing it to your Uno, you get a shell with some familiar looking filesystem and system commands, the ability to write to files though no editor, and a set of commands to control pins. It’s extremely basic, but you can see the potential.

If we were to speculate as to how this might become more useful then perhaps it might involve a more permanent filesystem perhaps on a flash chip. If possible, the ability to run script files containing a list of commands would also be very nice. Though we are guessing that maybe the reason these features are not in place lies in the meager specifications of an ATmega328, for which we can’t blame the developer at all. Even if it can’t be extended in this way though, it’s still a cool project.

We have to go back quite a while, but this isn’t the first time something like this has appeared on these pages.

GameCube Bot Records Your Play In A Weird Way

April 23, 2026 by 8 Comments

If you wanted to record yourself playing on a GameCube, you could use a VCR to capture the video output on tape. But there is a more interesting way to do it—which is precisely what [jiinurppa] built GameCube bot for. 

The concept is simple—GameCube bot is a small device that captures controller inputs and records them to an SD card. It can then play them back on command, allowing it to recreate gameplay as it happened the first time right on the console. A Raspberry Pi Pico is the brains of the operation, which is able to intercept signals from a standard GameCube controller. It’s paired with the aforementioned SD storage as well as an ST7735 display for showing status information. The device records in the DTM (Dolphin TAS Movie) format, which can be played back on the device when hooked up to a GameCube console, or in emulators like Dolphin itself.

[jiinurppa] notes that the device isn’t accurate enough to use for tool-assisted speed runs. Most notably, small errors in optical drive reads can lead to desyncs compared to the original machine state that make frame-accurate replays impossible. Still, it’s a neat build that can be useful for capturing game play and later analysis.

We’ve explored the world of Tool Assisted Speedruns before, though this device isn’t directly applicable to that world. Video after the break.

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Making RAM At Home In Your Own Semiconductor Fab

April 22, 2026 by 5 Comments

There’s little point in setting up your own shed-based clean room for semiconductor purposes if you don’t try to do something practical with it. Something like responding to the RAMpocalypse by trying to make your own RAM, for example.

Testing the DRAM cells. (Credit: Dr. Semiconductor, YouTube)
Testing the DRAM cells. (Credit: Dr. Semiconductor, YouTube)

After all, what could be so hard about etching the same repeating structures over and over? In a recent video, [Dr. Semiconductor]’s experience doing exactly this are detailed, with actual DRAM resulting at the end.

We covered the construction of the clean room shed previously, which should provide at least the basic conditions to produce semiconductors without worrying about contaminating dies. From here the process is reminiscent of etching PCBs, with a prepared surface coated with photoresist. Using UV exposure through a mask, the pattern is etched into the photoresist and from there the pattern is subsequently etched into the wafer’s surface.

With the patterns formed, the next step is doping of the silicon in order to create the active structures, i.e. the transistors and capacitors. Doping can be done in a variety of ways, with ion implantation being the industry standard method, but a bit too expensive and bulky for a shed fab. Instead a spin-on-glass method was used. After this the remaining functional structures can be built up.

If anyone was expecting to see a DDR5 DRAM die pop out at the end, they’re bound to be disappointed. The target here was to create a 5×4 array of DRAM cells, for a dizzying 20 bits. Still, the fact that it’s possible to DIY DRAM like this at home is already pretty awesome, with clearly plenty of room to push it towards and past fabrication nodes of the 1990s and beyond.

Although the produced DRAM cells have fairly leaky capacitors, they’re good enough for their purpose, and the plan is to scale up to a large DRAM array from here. Whether the DRAM control logic will also be implemented in hardware like this remains to be seen, but the video’s ending makes it clear that the goal is to attach it to a PC somehow.

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